During the next fiscal year, we shall concentrate our effort to regulate IgE antibody response in the mouse. First of all, experiments will be continued to study suppressor T cells which were raised by injections of urea-denatured ovalbumin in BDF1 mice. As we have shown that these cells suppressed primary IgE antibody response to ovalbumin, experiments will be carried out to depress the on-going IgE antibody response by the transfer of suppressor T cells. Attempts will be made to generate suppressor T cells by culture of normal spleen cells in vitro. As we have recently succeeded in priming helper T cells in vitro, which collaborate with IgE-G cells for the formation of IgE antibody, experimental conditions for the culture will be modified for the induction of suppressor T cells. The third approach is to obtain fragments of ovalbumin which maintain immunogenic determinants for T cells. It is hoped that some of these fragments might be effective for the generation of suppressor T cells specific for ovalbumin. BIBLIOGRAPHIC REFERENCE: Regulation of antibody response in vitro. Induction of secondary anti-hapten IgG antibody response by anti-immunoglobulin and enhancing soluble factor. Kishimoto, T. and Ishizaka, K. J. Immunol., 114:585, 1975. Reaginic antibody formation in the mouse. Adoptive anti-hapten IgE antibody reponse by dinitrophenyl keyhole limpet hemocyanin-primed spleen cells cultured with dinitrophenyl heterologous carrier conjugate. Okudaira, H. and Ishizaka, K. J. Immunol., 114:615, 1975.